A woman of mass 60 kg is standing in a lift at a shopping centre. The lift is at rest.
The lift is at rest.?
State the value of the weight of the woman.
Calculate the force required to accelerate a mass of 60 kg at 2.5m/s².
The lift accelerates upwards at 2.5m/s².
Calculate the force exerted on the woman by the floor when the lift is accelerating.
The lift reaches a steady upward speed.
State the value of the force exerted on the woman by the floor at this steady
speed.

a and c

c is 100% but i am confused in a

because growing process had stoped after 4-5 year

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

it is b. absorbs thermal energy